Evaporator



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Patented July 30, 1935 UNITED STATES PATENT orrlc's EVAPORATOBApplication October 18, 1934, Serial No. 748,960 7 Claims. (Cl. 62-126)This invention relates to improvements in evaporators and, moreespecially, an evaporator for use in refrigerating apparatus.

The invention is particularly applicable to refrigerating apparatus inwhich lubricating oil is mixed with the refrigerant. This is more orless common practice in many types of refrigerating apparatus. When oilis thus used, however, difficulty has been encountered in someevaporators 1o heretofore used because of the formation of an oil filmon the liquid refrigerant which hindered or lessened evaporation orboiling of such refrigerant. In our improved evaporator, this objectionis lessened or overcome.

Among the features of our invention is the provision of an evaporatorthat is simple in construction, cheap to manufacture and efllcient inoperation.

Another feature of our invention is the provision of a plurality ofboilers connected in series, with the refrigerant entering one boiler atthe bottom and leaving at the top. In this construction, a tubeconnecting two boilers will carry a certain amount of refrigerant in agaseous state and, also, a certain amount of liquid, namely, the amountof liquid to be evaporated in the following boiler or boilers.Consequently, the gas which bubbles up in a boiler has a tendency tobreak up or disturb any oil film on the surface of the liquidrefrigerant that otherwise might form. In this manner, retardation ofboiling or evaporation by oil film is prevented or lessened. This isespecially true of the last boiler, which may contain more oil than thepreceding boilers, particularly if the evaporators should happen to becharged with an amount of refrigerant not quite suflicient to raise theliquid level close enough to the end of the outlet tube. Therefore, theoperation of this type of evaporator is 40 not as dependent on a correctcharge of refrigerant as an ordinary single boiler type.

We have found that connection of the boilers in series createssubstantially free boiling of refrigerant in all the boilers soconnected. This 45 is due to the fact that in the first boiler, intowhich the liquid enters, the boiling will be unhindered by any oil film,due to the fact that the top of the liquid is continually skimmed offand goes into the second boiler. The boiling of liquid 50 in the secondboiler is also substantially unhindered by oil film, due to the factthat the gas which is evaporated in the first boiler continuously breaksup the oil film by bubbling up through it. 1

In these forms of devices embodying the features of our invention shownin the accompanying drawings- Figure 1 is a top plan view; Fig. 2 is aview, partly in side elevation and partly in section; Fig. 3 is an endview; Figs. 4, 5 and 6 are views similar to Figs. 1, 2 and 3,respectively, showing a modified form; Figs. 7, 8 and 9 are viewssimilar to Figs. 1, 2 and 3, respectively, showing another modification;Fig. 10 is a view, partly in front elevation and partly in section,showing another modification; Fig. 11 is a. bottom plan view of thesame; Fig. 12 is a view of the same in side elevation; and Fig. 13 is aview taken as indicated by the line l3 of Fig. 11.

In each of the devices shown in Figs. 1 to 9, inclusive, the evaporatorcomprises, in general,

'a sheet of metal in a U-shape with two cylindrical boilers or tubesinside about half way up lying side by side in the same horizontalplane. The lower portion of the sheet metal forms a lower shelf for anice tray, and the two boilers may receive another ice tray on top ofthem, thus forming an upper shelf for this purpose.

In the evaporator shown in Figs. 1, 2 and 3, the sheet metal I isgenerally bent into a U- shape, as shown in Fig. 3, with the upper edgesof the sides bent outwardly, as indicated by II, II to form attachingflanges provided with suitable holes l2 to receive the bolts, screws, orthe like, to attach the evaporator to any suitable support above it.Portions of the side walls of the device shown in Figs. 1, 2 and 3 arebent inwardly to form the two cylindrical boilers l3, l3 lying side byside. The ends of these boilers are closed by suitable convex heads l4,l4 suitably welded, brazed or otherwise fastened in place.

It will be seen that by this construction a single sheet of metal isused to form the entire U- shaped members and both boilers, with theexception of the heads. It is to be understood that where the bent edgesof the sheet metal come together at the sides, as indicated by l in thedrawings, the adjacent folded edges of the sheet metal are suitablysoldered, brazed or welded.

The bottom portion I6 of the U-shaped member may form a bottom shelf foran ice tray 11, and another ice tray 18 may be placed on top of the twoboilers, the latter thereby serving as an upper shelf for such tray.

is indicates an inlet pipe for the evaporator and where this enters theboiler l3, there may be provided a check valve 20, if desired. The inletpipe enters the bottom of one end of the boiler l3. Refrigerant leavesthe top of this boiler at the other end through the pipe 2| which entersthe bottom of the boiler l3. Refrigerant leaves the evaporator throughthe pipe 22 at the top of the boiler i3 at the end opposite the pipe 2|.The outlet pipe 22 may be bent into lower and upper loops 22 and 22,respectively, in order to give this pipe an opportunity to pick up acertain amount of heat from the cabinet, thereby applying superheat tothe gaspassing through the tube so that the latter will not frost up orsweat where it leaves the cabinet.

In the evaporator shown in Figs. 4, 5 and 6, there is also a U-shapedmember made of sheet metal H with the attaching flanges Ill providedwith holes H2. The sides of this member, however, are not bent inwardlyto form the cylinders, but separate cylinders H3 and H3 are employed.The bottom of the U-shaped member is indicated by HG, which may serve asa shelf for an ice tray (not shown) and another ice tray (not shown) maybe supported on top of the boilers H3 and H3. The ends of 'the twoboilers, as shown in Fig. 9.

the boilers are closed by suitable heads Ill.

The side walls of the U-shaped member are convexly curved where they lienext to the boilers, as indicated by I It, to give good heat exchangecontact with said boilers. This curvature, for example, may be carriedfor substantially 90 around the circumference of each boiler, and at theends of the curved portions, the

sheet metal may be welded or brazed to the boilers, as indicated by H5.

The evaporator shown in Figs. 4, and 6 is provided with inlet, outletand connecting tubes in the same manner as the evaporator of Figs. 1, 2and 3, said tubes being indicated by the same reference numerals,augmented by 100.

The evaporator shown in Figs. 7, 8 and 9 is generally similar to theothers above described, except for the method of forming the boilers.Here, again, there is a U-shaped member formed of sheet metal 2m withattaching flanges 2 provided with the holes 2|2. In this construction,two pieces of sheet metal are employed, an upper piecej'with its bottomcarried entirely across to form the upper halves of the boilers 2 l3 and2"". A separate piece of sheet metal is employed to form the bottomshelf 2 l6 and the lower halves of As here shown, the boilers are notprovided with separate heads, but the ends are closed by drawing downthe sheet metal to bring the edges together, as indicated by 2 (see Fig.8). Where the edges join at the ends and also at the sides of theboilers and in the middle between the two boilers, the adjacent edges orfaces of metal are suitably welded or otherwise fastened, as indicatedby 215.

The evaporator of Figs. '7, 8 and 9 is here shown as provided with aninlet pipe 220 which enters one boiler at one end near the bottom. Thisboiler is connected at its other end near the top by a pipe 22l with theadjacent end of the adjoining boiler at the bottom, and the latter isprovided with an outlet pipe 222 at the other end at the top.

In the evaporator shown in Figs. 10 to 13, inclusive, there is provideda single flat shelf instead of a U-shaped member. This shelf is made ofsheet metal and under it are located four horizontally-arranged boilersside by side in the same horizontal plane. The sheet metal shelf we haveindicated by 3M and the boilers by M3, M3, 2H3 and 3l3 The side edges ofthe shelf 3 I 0 are bent downwardly to form attaching flanges 3i Iprovided with the slots 3|2to hook over suitable fastening devices (notshown). Where the shelf 3! rests on top of the boilers, it is providedwith convexly curved portions 3 l 0 contacting with the boilers throughsubstantially 90 to give good heat' exchange relation between the sheetmetal piece 3 0 and the boilers. The edges of the curved portions may bewelded, soldered or brazed to the boilers, as indicated by M5.

In the evaporator of Figs. 10 to 13, inclusive, 3 I 9 indicates theinlet pipe and 320, an expansion valve. The refrigerant enters theboiler M3 at one end at the bottom, leaving at the opposite end at thetop through the pipe 32l which enters the adjacent end of the nextboiler at the bottom.

The refrigerant leaves the opposite end of this boiler at the topthrough the pipe 322, entering the next boiler at the bottom. .In thesame way, the refrigerant leaves the boiler 3| 3 at the top through thepipe 323, entering the last boiler 3l3 at the bottom. 324 indicates theoutlet pipe from the evaporator which leaves the last boiler 313 at thetop at the end opposite where the pipe 323 enters.

It will be seen that there are several features common to all the formsof evaporator shown. For example, the use of a plurality of cylindricalboilers arranged side by side parallel to each other in the samehorizontal plane connected in series with the refrigerant entering oneboiler at the top at one end and leaving at the bottom of the oppositeend. Also, the use of boilers and a piece of sheet metal in good heatexchange relation to the same to assist conduction of heat from thespace being cooled to the boilers.

The evaporators shown in Figs. 1 to 9, inclusive, are similar in thesense that in each case there is a substantially U-shaped member made ofsheet metal with two cylindrical boilers inside about midway between thetop and bottom. In the three forms shown in these figures, however,different methods are employed in the formation of the boilers. In theevaporators of Figs. 1 to 3 and Figs. 7 to 9, the sheet metal whichforms the U- shaped member is also used to form the side walls of theboilers. In the device of Figs. 4 to 6, separate tubes are employed toform the boilers and the sides of the U-shaped member are curved tocontact the sides of these boilers.

It will be seen that in each of the evaporators shown in Figs. 1 to 13,inclusive, the sheet metal has curved portions adjacent the cylindricalboilers in order to give good heat exchange relation therewith. Thisheat exchange relation is accomplished in diflferent ways in thedifferent forms, but the result is the same in each. In the evaporatorsof Figs. 4 to 6 and Figs. 10 to 13, the boilers are formed of separatetubes, but the sheet metal has curved portions closely contacting thewalls of said tubes. In the other devices, the sheet metal itself iscurved to form the walls of the boilers.

While we have shown and described certain embodiments of our invention,it is to be understood that it is capable of many modifications.Changes, therefore, in the construction and arrangement may be madewithout departing from the spirit and scope of the invention asdisclosed in the appended claims, in which it is our intention to claimall novelty inherent in our invention as broadly as permissible, in viewof the prior art.

What we claim as new, and desire to secure by Letters Patent, is:

1. An evaporator including a plurality of cylindrical boilers and apiece of sheet metal having curved portions adjacent said boilers and incontact therewith to give good heat exchange relation therewith.

2. An evaporator, including; a U-shaped piece of sheet metal; and a pairof horizontal boilers lying inside thereof connected in series.

3. An evaporator, including; a U-shaped piece of sheet metal; and aplurality of horizontal boilers lying inside thereof about half-waybetween the top and bottom.

4. An evaporator, including; a U-shaped piece of sheet metal; and aplurality of horizontal boilers lying inside thereof in the same planeabout half-way between the top and bottom.

5. An evaporator, including; a U-shaped piece of sheet metal withportions of the sides thereof bent to form the walls of cylindricalboilers lying inside thereof about half-way between the top and bottom.

6. An evaporator, including; a U-shaped piece of sheet metal withportions of the sides thereof bent to form two horizontal boilers lyingin the same plane inside of said U-shaped member about half-way betweenthe top and bottom thereof.

'1. An evaporator, includinz; a plurality of horizontal boilersconnected in series and lying in substantially the same horizontalplane; and a piece of sheet metal on top of said boilers and in goodheat exchange relation therewith.

JENS TOUBORG. HOMER E. ROBEBROOK.

